The conventional way to track a discrete object is to convert the image of that target to electrical signals by a detector such as a vidicon. In the prior art the tracking circuits have been activated for a time corresponding to a rectangular area which included the selected target. Normally, a rectangular area will not closely fit an odd-shaped target and will include some background area. This may permit the tracking of the original target to be overcome by some pictorial element of the background. Therefore, there is a need for the present invention which prevents background details from having any affect on the tracking action by opening the tracking circuits just during the time the pictorial signal represents a coherent area on the selected object.